Slide clamp for machine tools



0, 1954 J. M. WALTER SLIDE CLAMP FOR MACHINE TOOLS Filed Oct. 7, 1948 INVENTOR. Joy/v M Milan's-1g, BY Q4 m ATTORNEYS- Patented Aug. 10, 1954 SLIDE CLAMP FOR MACHINE TOOLS John M. Walter, Cincinnati, Ohio, assignor to The G. A. Gray Company, Cincinnati, Ohio, a

corporation of Ohio Application October 7, 1948, Serial No. 53,360

6 Claims.

This invention relates to a slide clamp for machine tools. While it is applicable to a number of situations, I have found it particularly useful in connection with clamping the tool slide of a planer to the so-called harp, which in turn rides on the rail.

In the industry considerable trouble has been had in the past in clamping tool slides in such a Way as to avoid chatter. The clamp according to the present invention overcomes difficulties of this sort and is yet extremely simple in construction.

It is a further objective of the present invention to provide a clamp, and more particularly a clamp for planer tool slides, which will securely clamp two relatively sliding parts together against relative movement.

It is another object of the present invention to provide a clamp as outlined above which will exert a clamping effort tending to rock the slide on its ways so as to bring into intimate engagement the contact surfaces of the ways on the side opposite the clamp.

A further object of my invention involves the process of a clamp having one clamping face at an angle to the other clamping face, whereby to produce such a rocking moment.

Further objects of the invention include the provision of a clamp of the character outlined which will be extremely simple in construction.

These and other objects of my invention I accomplish by that certain construction and arrangement of parts of which I shall now describe certain exemplary embodiments.

Reference is made to the drawings forming a part hereof and in which:

Figure 1 is a fragmentary front elevation of a planer rail showing the harp and tool slide to which my invention is applied.

Figure 2 is a cross-sectional view through the rail on the line 2-2 of Figure 1 showing the harp and slide in side elevation.

Figure 3 is a cross-sectional view on an enlarged scale taken on the line 3-3 of Figure 1, and

Figure 4 is a view similar to Figure 3 to a smaller scale showing a modification.

Since the present invention applies only to the clamp I shall describe the rest of the apparatus only in so far is necessary to an understanding of the present invention.

The rail is shown generally at [0. A head H is arranged to slide thereon in conventional manner and the head H carries the harp l2. The harp l2 may be set at various angles as is well known. The tool slide I3 is adjustably mounted on the harp and carries the usual tool block M.

In Figure 3 the harp I2 is provided with the dovetail recess l5 and the tool slide is provided with the extending dovetail portion l6 arranged to slide within the recess 15. Movement of the tool slide !3 with relation to the harp is provided as well known by means of the screw ll, but this mechanism need not be described further.

At this point it should be noted that during a planing operation the tool pressure will have two components; one component will be toward the right of Figure 3 and one toward the top of the figure. It will be understood that Figure 3 shows the right hand head and in accordance with conventional planer practice this head is always fed from left to right and of course, the operator stands at the right. The component of the tool pressure which is directed toward the top of Figure 3 is carried by the flat surfaces 3!, 32 on both sides of the dove-tail while the tool pressure opponent which is toward the right of the figure is carried by the angular dove-tail surfaces at the right of the figure.

When the tool slide is properly adjusted for the job by hand it must be clamped to the harp, so as to secure it against movement in relation thereto. For this purpose I provide one or more clamps, one of which is shown in detail in Figure 3. A stud I8 is threaded into a threaded hole 59 in the tool slide and over the stud i8 is passed the clamping lever 28 which is held in place and tightened by means of a nut 21!. The nut 2! has a spherical face 22 and the clamping lever 20 has a spherical recess 23 so that cooperation between the surfaces 22 and 23 produces in effect a ball and socket joint. The bore 24 through the member 2!! is oversize as is clearly apparent in the drawings.

One end of the clamping lever as at 33 is arranged to bear against the tool slide by means of a clamping face 25. It is provided with a recess 26 for engagement with a pin 27 seated in a hole in the tool slide. The pin 2i thus serves to prevent the clamping lever ill from swivelling out of position when it is unclamped. The clamping lever also has a clamping portion 28 arranged to bear against a portion of the harp #2. It will be noted that the clamping face it is disposed at an angle to the clamping face 25, and for this purpose the harp is provided with a bearing surface 33 disposed at a corresponding angle. Preferably the angle between the face 25 and the face 38 is about 10. In other words, it may be considered that the angle between the clamping faces constitutes an obtuse angle of about The exact angle is not critical, but I have found that an angle of about 10 is sunlcient to produce the desired effect, and it is therefore unnecessary to make the angle any greater.

The result of the construction thus far described is that when the nut 2| is tightened the portion 28 exerts a clamping thrust toward the left and upward, as seen in Figure 3, the reaction being a turning moment of the clamping lever in a clockwise direction, so that the portion 33 exerts a thrust toward the left as in Figure 3, thereby bringing the contact surfaces at 3! and 32 into intimate engagement. I have found that maintaining of tight engagement between the surfaces 31 and 32 on the side of the ways opposite the clamping lever eliminates chatter when the tool is taking a bite.

When the bolt 2i is tightened the tool slide it is drawn toward the right of Figure 3. As a result of this the mating dove-tail surfaces at the right are drawn tightly together and prestressed. As a result of a sort of wedging action the flat surfaces 3t, 32 at the right of the dove-tall are also prestressed. However, the tendency of drawing the tool slide toward the right is to make for a small amount of clearance between the dove-tail surfaces at the left and this loosening of the dove-tail surfaces at the left is accompanied by a loosening of the hat surfaces 3!, 32, at the left of the dove-tail which would result in chatter. Because of the counterclockwise moment imparted to the tool slide by the illustrated construction the flat surfaces 3!, 3?: at the left of the figure are brought tightly against each other and chatter is avoided Clamping face 23 may be constituted of a difierent material than the clamping lever, if desired, so as to prevent marring of the surface 39.

In Figure I have shown a modification to illustrate that a clamping device according to my present invention may equally well be applied. where the extending dovetail structure is on the harp and the dovetail recess is on the tool slide. The effect is exactly the same as before in that the meeting surfaces rm and 32a are maintained tightly in contact. The angle of the clamping portion 28 must of course be reversed.

InFigure 4 it will be clear that a tightening of the nut 22 produces a tightening of the dovetail surfaces at the left of the figure, and by a wedging action a tightening of the flat surfaces 3ia, 32a at the left of the figure. This is, of course, accompanied by a loosening of the dove-tail surfaces at the right of the figure, and again chatter would be present were it not for the rotational moment which causes the fiat surfaces 31a, 32a at the right of the figure, to be tightened. This is why the angle of the clamping surfaces is reversed with respect to that in Figure 3, and the reversal is necessitated by the fact that the extending dove-tail is on the harp in Figure 4, while it is on the slide in Figure 3.

In all other respects the clamping device of Figure 4 is the same as that of Figure 3.

It will be clear that numerous modifications may be made without departing from the spirit of my invention, and that details of the clamping element may be varied while still achieving the benefits of my invention. As pointed out above, the angle between the bearing surface of the clamping lever may be varied as well, and I therefore do not intend to limit myself except as clearly set forth in the claims which follow.

Having now described my invention, what I claim as new and desire to secure by Letters Patent is:

1. In a machine tool having two elements one of which is slidable in relation to the other along cooperating dovetailed way surfaces, a for securing said slidable element against sliding movement, comprising a clamping lever disposed to one side of the axis of said ways, a screw rockingly securing said clamping lever to said slidable element, said lever having a portion arranged to bear against said slidable element, and having also a portion arranged to bear against the other of said elements, an additional bearing surface for said last named portion on said other element, said additional bearing surface, and said portion arranged to bear thereagainst, being angularly disposed, so as to provide a clamping force at an angle to the clamping force of said first mentioned portion, so as to tend to rotate said slidable element with respect to said other element about the axis of said ways.

2. The structure of claim 1, in which the angle between the bearing faces of the said portions of the clamping lever form an obtuse angle, whereby a rocking component is applied to said one element to produce tight contact between those of said. way surfaces which bear the tool thrust.

3. The structure of claim 2, in which said obtuse angle is on the order of i. In a planer having a harp with a tool slide mounted thereon for sliding movement by means of engaging dovetailed way surfaces, a clamp for securing said slide against movement relative to said harp, comprising a clamping lever disposed to one side of the axis of said ways, a screw rockingly securing said clamping lever to said slide, said lever having a portion arranged to bear against said slide and having also a portion arranged to bear against said harp, an additional bearing surface for said last named por tion on said harp, said additional bearing surface, and said portion arranged to hear thereagainst, being angularly disposed, so to provide a clamping force at an angle to the clamping force of said first named portion, so as to tend to rotate said slide with respect to said harp about the axis of said ways.

5. The structure of claim 4, in which the angle between the bearing faces of said portion of the clamping lever form an obtuse angle, whereby a rocking component is applied to said slide about the axis of said way surfaces to produce tight contact between those of said way surfaces which bear the tool thrust.

6. The structure of claim 5, in which said obtuse angle is on the order of 170.

References @ited in the file of this patent UNITED STATES PATENTS Number Name Date 1,340,741 Schmelzer May 18, 1920 1,354,438 Jewsbury Get. 5, 1920 1,6 0,767 Greenleaf et a1. Aug. 1 2 1,358,898 Mesker May 1'7, 1932 1,981,263 Croft Nov. 20, 1934 2,441,533 Montgomery May 11, 1948 2,466,596 Krause Apr. 1949 FOREIGN PATENTS Number Gountry 884,788 France May 1943 3, 43 France Mar, 6, 1944 

